Resizing images with PHP（Php生成缩略图）

The following script will easily allow you to resize images using PHP.

下面的Php代码能够非常容易的让你生成缩略图

<?php /** File: SimpleImage.php* Author: Simon Jarvis* Copyright: 2006 Simon Jarvis* Date: 08/11/06* Link: http://www.white-hat-web-design.co.uk/articles/php-image-resizing.php** This program is free software; you can redistribute it and/or* modify it under the terms of the GNU General Public License* as published by the Free Software Foundation; either version 2* of the License, or (at your option) any later version.** This program is distributed in the hope that it will be useful,* but WITHOUT ANY WARRANTY; without even the implied warranty of* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the* GNU General Public License for more details:* http://www.gnu.org/licenses/gpl.html**/ class SimpleImage {     var $image;    var $image_type;    function load($filename) {        $image_info = getimagesize($filename);        $this->image_type = $image_info[2];        if( $this->image_type == IMAGETYPE_JPEG ) {            $this->image = imagecreatefromjpeg($filename);        } elseif( $this->image_type == IMAGETYPE_GIF ) {            $this->image = imagecreatefromgif($filename);        } elseif( $this->image_type == IMAGETYPE_PNG ) {            $this->image = imagecreatefrompng($filename);        }    }    function save($filename, $image_type=IMAGETYPE_JPEG, $compression=75, $permissions=null) {        if( $image_type == IMAGETYPE_JPEG ) {            imagejpeg($this->image,$filename,$compression);        } elseif( $image_type == IMAGETYPE_GIF ) {            imagegif($this->image,$filename);        } elseif( $image_type == IMAGETYPE_PNG ) {            imagepng($this->image,$filename);        }        if( $permissions != null) {            chmod($filename,$permissions);        }    }    function output($image_type=IMAGETYPE_JPEG) {        if( $image_type == IMAGETYPE_JPEG ) {            imagejpeg($this->image);        } elseif( $image_type == IMAGETYPE_GIF ) {            imagegif($this->image);        } elseif( $image_type == IMAGETYPE_PNG ) {            imagepng($this->image);        }    }    function getWidth() {        return imagesx($this->image);    }    function getHeight() {        return imagesy($this->image);    }    function resizeToHeight($height) {        $ratio = $height / $this->getHeight();        $width = $this->getWidth() * $ratio;        $this->resize($width,$height);    }    function resizeToWidth($width) {        $ratio = $width / $this->getWidth();        $height = $this->getheight() * $ratio;        $this->resize($width,$height);    }    function scale($scale) {        $width = $this->getWidth() * $scale/100;        $height = $this->getheight() * $scale/100;        $this->resize($width,$height);    }     function resize($width,$height) {        $new_image = imagecreatetruecolor($width, $height);        imagecopyresampled($new_image, $this->image, 0, 0, 0, 0, $width, $height, $this->getWidth(), $this->getHeight());        $this->image = $new_image;    }       }

（Usage）用法

Save the above file as SimpleImage.php and take a look at the following examples of how to use the script.

保存上面的代码，文件名为SimpleImage.php，看下面的例子如何使用脚本

The first example below will load a file named picture.jpg resize it to 250 pixels wide and 400 pixels high and resave it as picture2.jpg

第一个例子加载一个名为picture.jpg的图片，并且重新缩放为250×400px的图片，另存为picture2.jpg

<?php    include('SimpleImage.php');    $image = new SimpleImage();    $image->load('picture.jpg');    $image->resize(250,400);    $image->save('picture2.jpg');

If you want to resize to a specifed width but keep the dimensions ratio the same then the script can work out the required height for you, just use the resizeToWidth function.

如果你想Resize一个图片，并且指定宽度保持宽高比例，那么你可以采用resizeToWidth这个方法

include('SimpleImage.php');$image = new SimpleImage();$image->load('picture.jpg');$image->resizeToWidth(250);$image->save('picture2.jpg');

You may wish to scale an image to a specified percentage like the following which will resize the image to 50% of its original width and height

如果你要按照指定的百分比来Resize图片

include('SimpleImage.php');$image = new SimpleImage();$image->load('picture.jpg');$image->scale(50);$image->save('picture2.jpg');

You can of course do more than one thing at once. The following example will create two new images with heights of 200 pixels and 500 pixels

你可以同时处理更多的事情。下面的例子就是创建了两个新的图片，高度分别为200px和500px

include('SimpleImage.php');$image = new SimpleImage();$image->load('picture.jpg');$image->resizeToHeight(500);$image->save('picture2.jpg');$image->resizeToHeight(200);$image->save('picture3.jpg');

The output function lets you output the image straight to the browser without having to save the file. Its useful for on the fly thumbnail generation

直接浏览器输出图片，并不保存为文件按，这对于联机生成缩略图非常有用

header('Content-Type: image/jpeg');include('SimpleImage.php');$image = new SimpleImage();$image->load('picture.jpg');$image->resizeToWidth(150);$image->output();

The following example will resize and save an image which has been uploaded via a form

下面的例子Resize了一个从form上传的图片

<?php   if( isset($_POST['submit']) ) {       include('SimpleImage.php');      $image = new SimpleImage();      $image->load($_FILES['uploaded_image']['tmp_name']);      $image->resizeToWidth(150);      $image->output();   } else { ?>    <form action="upload.php" method="post" enctype="multipart/form-data">      <input type="file" name="uploaded_image" />       <input type="submit" name="submit" value="Upload" />    </form> <?php   }?>

Further Information（补充信息）

This script will eventually be developed further to include functions for easily sharpening, bluring, cropping, brightening and colouring images.
If you have any problems using this script please email us.
If you find this script useful then please consider making a donation to the developer

参考链接地址：

http://www.white-hat-web-design.co.uk/blog/resizing-images-with-php/